You may want an element in there for the original network that aired it, too.
Some general thoughts:
* Actors, writers, directors, and producers are all people. You will want similar information for each, such as first name, last name, and a list of seasons in which they appeared/worked. To that end, I would have a generic "person" type that has those fields, and then you'd put collections of those under each type of person. So, the "actor" element is a collection of type "person".
* The above obviates the need for the "seasonnr" element, which is confusing and seems to be of limited utility. In its place, each person can have a collection of season numbers indicating when they worked on the show.
* The "year" field makes no sense by itself. Shouldn't you have "yearbegan" and "yearended"?
* If you want this to be a comprehensive TV series schema, you should also have a "season" type which is a collection of "episode" elements, and for each "episode" you would have the following information: season, episode number, production number (optional?), writer(s) (collection), guest stars (collection), title, original air date, synopsis. For the sake of normalization, I suppose you could get away with only using the IDs of any people involved in a given episode, rather than duplicating the entire "person" object for each one. The overall "person" collections would be outside the "episode" and "season" collections. I know you already have some of this info in your schema, I'm just suggesting how you could reorganize/expand it to be more logical and complete.
A big part of my job is designing schemas and normalizing data so I enjoy this stuff.
Hope you get something out of my suggestions!